Atraumatic stent with reduced deployment force, method for making the same and method and apparatus for deploying and positioning the stent

ABSTRACT

An implantable stent includes a plurality of elongate wires braided to form a hollow tubular structure having a tubular wall to define an interior surface and an exterior surface and having opposed open first and second ends, wherein the opposed open first and second ends are atraumatic ends The atraumatic ends of the stent are desirably free of any loose wire ends. The wires include composite wires to enhance visibility of the wires to provide improved external imaging of the wires in the body. The elongate composite wires of the stent may be metallic wires having an outer metallic portion including a first metal, such as nitinol, and an inner metallic core portion including a second metal, which is a radiopaque material, such as gold, barium sulfate, ferritic particles, platinum, platinum-tungsten, palladium, platinum-iridium, rhodium, tantalum or combinations thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/271,774, filed Nov. 10, 2005, which claims the benefit of U.S.Provisional Application No. 60/626,729, filed Nov. 10, 2004, and U.S.Provisional Application No. 60/680,630, filed May 13, 2005, the contentsof all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a stent having atraumatic looped endswith smooth stent wire ends and improved stent wire welds. The presentinvention also relates to an apparatus for deploying and positioning theatraumatic stent.

BACKGROUND OF THE INVENTION

Stents made from interconnecting, often braiding, elongate wires may bemade less traumatic, i.e., atraumatic, by closing the loose wire ends atthe ends of the stents. The loose wire ends have typically been closedby mechanical means, for example by welding. Such mechanical means,however, often have sharp ends which may score the inside of a deliverysystem from which it is deployed or may also irritate bodily vessels orlumens in which the stent is placed. Further, the welds of prior artstent devices may fatigue over time leading to undesirable failure.

Thus, there is a need in the art for a stent made from elongate wires ina closed-end design while avoiding the disadvantages of the prior art.More particularly, there is a need in the art for improved stent weldsand less traumatic welded stent wire ends.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an implantable stent isprovided. The stent includes a plurality of elongate wires braided toform a hollow tubular structure having a tubular wall to define aninterior surface and an exterior surface and having opposed open firstand second ends, wherein the opposed open first and second ends areatraumatic ends, and further wherein the wires include composite wiresto enhance visibility of the wires to provide improved external imagingof the wires in the body. Desirably, the enhanced visibility is enhancedradiopacity and the external imaging is fluoroscopic or x-rayvisualization.

The atraumatic ends of the stent are desirably free of any loose wireends.

The elongate composite wires of the stent may be metallic wires havingan outer metallic portion including a first metal and an inner metalliccore portion including a second metal, wherein the first metal isdifferent from the second metal. Desirably, the second metal of theinner core includes a radiopaque material selected from gold, bariumsulfate, ferritic particles, platinum, platinum-tungsten, palladium,platinum-iridium, rhodium, tantalum or combinations thereof. The firstmetal of the outer portion may include nitinol.

The stent of this aspect of the present invention desirably may alsohave wires that terminate at the second end, wherein the wires at thefirst end are arranged in a series of closed loops with each loop havingan apex defined by a bend in one of the wires and having an opposed basedefined by crossing of adjacent wires, and further wherein the apex ofadjacent closed loops are longitudinally offset from one and the other.

The stent of this aspect of the present invention desirably may alsohave wires that terminate at the second open end, and adjacentlyjuxtaposed wires are securably joined at the second open end to providefirst securably joined regions, wherein at least one of the adjacentlyjuxtaposed stent wires are extended past the first securably joinedregions and further wherein the extended and looped wire is securablyjoined to the proximal pair of wires with second securably joinedregions to define closed loop wire ends. Desirably, the wires aresecurably joined by welding the wired and further wherein the securablyjoined regions are welds.

The stent of this aspect of the present invention desirably may alsohave wires that terminate at the second open end, and further whereinadjacently juxtaposed wires at the second open end are securably joinedto provide securably joined regions, wherein ends of the terminatedwires are smoothed to remove sharp edges from the wire ends. Desirably,the wires are securably joined by welding the wired and further whereinthe securably joined regions are welds.

The stent of this aspect of the present invention desirably may alsohave wires that terminate at the second open end, and adjacentlyjuxtaposed wires are securably joined at the second open end to providefirst securably joined regions, wherein at least one of the adjacentlyjuxtaposed stent wires are extended past the first securably joinedregions and looped such that the extended end abuts a proximal pair ofstent wires; and further wherein the extended and looped wire issecurably joined to the proximal pair of wires with second securablyjoined regions which are longitudinally offset from the first securablyjoined regions. Desirably, the wires are securably joined by welding thewired and further wherein the securably joined regions are welds. Thefirst and the second welds may have a substantially same longitudinallyextending extend. The first and the second welds may have longitudinallyextending portions which overlap one and the other.

The stent of this aspect of the present invention may also be partiallyor fully coated with a polymeric material. The stent may further includehollow tubular graft disposed partially or fully over the interior orthe exterior surface. Desirably, the graft is a polymeric material. Thepolymeric material may be selected from polyester, polypropylene,polyethylene, polyurethane, polynaphthalene, polytetrafluoroethylene,expanded polytetrafluoroethylene, silicone, and combinations thereof.

In another aspect of the present invention, a method for making animplantable stent is provided. The method includes the steps of (i)providing a plurality of elongate wires, wherein the elongate wiresinclude composite wires to enhance visibility of the wires to provideimproved external imaging of the wires in the body; and (ii) braidingthe wires to form a hollow tubular structure having a tubular wall todefine an interior surface and an exterior surface and having opposedopen first and second ends, wherein the opposed open first and secondends are atraumatic ends. Desirably, the enhanced visibility is enhancedradiopacity and the external imaging is fluoroscopic or x-rayvisualization.

The method this aspect of the present invention may further include thestep of arranging the wires at the first end in a series of closed loopswith each loop having an apex defined by a bend in one of the wires andhaving an opposed base defined by crossing of adjacent wires, whereinthe apex of adjacent closed loops are longitudinally offset from one andthe other.

The method this aspect of the present invention may also further includethe steps of terminating the wires at the second end; aligning the wiresat the second end into a plurality of mated adjacent wires to define aplurality of juxtaposed regions; and securably joining the matedadjacent wires to one and the other at the juxtaposed regions to definea closed loop at the second end. Desirably, the step of securablyjoining the wires includes welding the wires.

The method this aspect of the present invention may further include thesteps of terminating the wires at the second end to form terminated wireends; aligning the wires at the second end into a plurality of matedadjacent wires to define a plurality of juxtaposed regions; securablyjoining the mated adjacent wires to one and the other at the juxtaposedregions to define a plurality of securably joined regions; and smoothingthe terminated wire ends by removing sharp edges from the wire ends.Desirably, the step of securably joining the wires includes welding thewires, and further wherein the securably joined regions are welds.

The method this aspect of the present invention may further include thesteps of terminating the wires at the second end; aligning the wires atthe second end into a plurality of mated adjacent wires to define aplurality of juxtaposed regions; extending at least one of the matedstent wires to provide an extended stent wire; looping the extendedstent wire so the extended end abuts a proximal pair of stent wires;securably joining the mated adjacent wires to one and the other at thejuxtaposed regions; and securably joining the extended and looped wireto the proximal pair of wires with a pair of longitudinally offsetsecurably joined regions. Desirably, the step of securably joining thewires includes welding the wires, and further wherein the securablyjoined regions are welds.

In another aspect of the present invention, a stent delivery anddeployment system is provided. The system includes a delivery catheterhaving a distal end; an elongate radially self-expanding stent having adistal end adjacent the distal end of the catheter; an elongate sheathretractably positioned about the stent so as to maintain the stent in aradially compressed delivery condition about the distal end of thecatheter; and a retaining band positioned adjacent the distal end of thestent, the retaining band being retractable with the sheath so as toallow longitudinally progressive and radial expansion of the stent uponthe retraction of the sheath for deploying the stent. The retaining bandmay include a radiopaque marker. The band may also be formed of aradiopaque material.

In yet another aspect of the present invention, a method of deliveringand deploying an expandable stent includes the steps of disposing aradially expanding stent at a distal end of a delivery catheter;positioning a retractable sheath having a retaining band adjacent adistal end of the stent over the stent so as to maintain the stent in aradially compressed delivery condition; and retracting the sheath andthe retaining band with respect to the distal end of the catheter toallow longitudinal progressive expansion of the stent. The sheath andthe band are retracted together. The retaining band may include aradiopaque marker or is formed of a radiopaque material. The positioningstep may further include the step of positioning the band at the distalend of the stent. Desirably, the stent is a braided stent having opposedfirst and second atraumatic open ends.

The stents, systems and methods of the present invention may be used atstrictures or damaged vessel sites. Such sites may suitably includebodily tissue, bodily organs, vascular lumens, non-vascular lumens andcombinations thereof, such as, but not limited to, in the coronary orperipheral vasculature, esophagus, trachea, bronchi, colon, biliarytract, urinary tract, prostate, brain, stomach and the like

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a hollow, tubular stent according to thepresent invention.

FIG. 2 is an expanded view of a wall portion of the stent of FIG. 1taken along the 2-2 axis showing a plurality of stent wires.

FIG. 3 depicts a braided stent with a closed-end loop design having aplurality of welds at the closed end according to the present invention.

FIGS. 4 and 5 are expanded views of weld areas of FIG. 3 illustratingsmooth terminated wire ends.

FIG. 6 is an expanded view of the weld of FIG. 3 showing a pair ofoffset welds joining three adjacently juxtaposed stent wires.

FIGS. 7-11 depict an arch with equilateral sides and an apex in aclosed-end loop design according to the present invention.

FIG. 12 depicts an exploded, partial view of the left-side stent end ofFIG. 3.

FIG. 13 depicts a mandrel having shaped pins for forming the closedloops of FIGS. 7-11.

FIG. 14 depicts a stent having a covering of silicone according to thepresent invention.

FIG. 15 is a cross-sectional view of the stent of FIG. 14 showing anouter covering of silicone about the stent.

FIG. 16 is a cross-sectional view of the stent of FIG. 14 showing aninner covering of silicone about the stent.

FIGS. 17-22 depict a stent deployment and delivery system of the presentinvention.

FIGS. 23-31 depict radiopaque marker placement details according to thestent deployment and delivery system of FIGS. 17-22.

FIG. 32 depicts a suture loop attached to a portion of the stent of thepresent invention.

FIG. 33 depicts the welding of looped and braided wires within the braidstructure of the stent of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 depicts stent 10 of the present invention. Stent 10 is a hollowtubular structure having opposed open ends 12, 14 and having a tubularwall 16 therebetween. A portion of the tubular wall 16 is depicted inFIG. 2 as having a plurality of elongate wires 18 formed into thetubular wall 16. The elongate wires 18 traverse the length of the stent10 in a direction traverse to the longitudinal length of the stent 10.The elongate wires 18 may be formed into the tubular wall 16 by braidingthe wires 18, winding the wires 18, knitting the wires 18, andcombinations thereof. Preferably, the wires 18 are braided to form thetubular wall 16.

As used herein the term braiding and its variants refer to the diagonalintersection of elongate filaments, such as elongate wires, so that eachfilament passes alternately over and under one or more of the otherfilaments, which is commonly referred to as an intersection repeatpattern. Useful braiding patterns include, but are not limited to, adiamond braid having a 1/1 intersection repeat pattern, a regular braidhaving a 2/2 intersection repeat pattern or a hercules braid having a3/3 intersection repeat pattern. The passing of the filaments under andover one and the other results in slidable filament crossings that arenot interlooped or otherwise mechanically engaged or constrained.

A joined or welded stent 10′ according to the present invention isdepicted in FIG. 3. The elongate wires 18 terminating at open end 12 aremated and adjacently mated wires are secured to one and the other bywelds 20 or by other suitable means. For example, the wires 18 may bewelded together through use of a welding material or the wires 18 may beheatingly and/or meltably fused together without the use of a weldingmaterial. Further, the wires 18 may mechanically joined, such as, butnot limited to, through the use of small-sized or micro-fabricatedclamp, crimpable tube, hypotube, and the like. The joining of threeadjacently mated wires 18 and the welding thereat is depicted in furtherdetailed in FIGS. 4-6. The positioning of adjacently mated wires to formclosed-loop end designs is further described in U.S. Application No.60/472,929, filed May 23, 2003, which was filed May 24, 2004 as U.S.application Ser. No. 10/852,495 and published as U.S. Patent ApplicationPublication No. 2005/0049682 A1, the contents of all of which areincorporated herein by reference. The stent 10′ depicted in FIG. 3includes 24 wires or filaments 18 of biocompatible material. The wiresare relatively thin at a diameter of about 0.01 inches. The number ofwires and the diameters of the wires, which may be the same ordifferent, depicted in FIG. 3 are not limiting, and other numbers ofwires and other wire diameters may suitably be used. Desirably, an evennumber of wires are used, for example from about 10 to about 36 wires.

The stent 10′ depicted in FIG. 3 has atraumatic open ends 12, 14. Asused herein, the phrase “atraumatic end” and it variants refer to aterminal end of a stent which is free of sharp wire ends or other sharpprojections or deformities which may cause trauma when implanted into abodily lumen. For example, as described in further detail below, openend 14 of the stent 10′ is atraumatic because the stent 10′ is braidedsuch that no ends of the wires 18 end at this end of the stent 10′. Inother words, stent 10′ may be braided such that all the ends of thewires 18 are distal from the end 14, for example, by commencing thebraiding of the stent 10′ with wires 18 that are bent in a smoothconfiguration so that the loop ends 15 of the end 14 have no sharp ortraumatically pointed bends or projections. Moreover, as described infurther detail below, the end 12 of the stent 10′ is atruamatic because,among other things, even though the wires 18 terminate proximal to theend 14 of the stent 10′, certain wires 18 are extended and looped backto provide an atruamatic end with, for example, no sharp ortraumatically pointed bends, no sharp wire ends, no other traumaticallysharp projections or deformities and the like.

Adjacently welded wires according to the present invention are depictedfurther detail in FIGS. 4-6. The terminated wire ends 19 a, 19 b and 19c are smoothed to remove sharp edges from the ends. As depicted in FIG.4, terminal wire ends 19 b and 19 c are diagonally cut to remove shapeedges as compared to wires that are not diagonally cut (not shown).Further, as depicted in FIG. 5, terminal wire end 19 a is smoothed to ahave a curved portion or a portion having a radius of curvature. Suchsmoothing may be achieved by use of a laser beam over the terminal end19 a. Heat generated by the laser beam melts the wire material forming asmooth, curved shape. Surface tension of the molten wire material allowsthe material to flow out evenly. These techniques for smoothing theterminal wire ends may be used individually or in combination. In otherwords, terminal ends 19 a, 19 b and 19 c may be, individually or incombination, diagonally cut and/or partially melted to provide a smoothterminal wire end. Additionally, the terminal wire ends 19 a, 19 b and19 c may be chemically or electro-chemically treated to remove sharpends. Details of chemically or electro-chemically removing processes aredescribed in U.S. patent application Ser. No. 10/845,844, filed May 14,2004, the contents of which are incorporated herein by reference.

Further, as depicted in FIGS. 4-5, a securably joined region or weld 20a joins wires 18 a and 18 b, and a securably joined region or weld 20 bjoins wires 18 b and 18 c. Securably joined regions or welds 20 a and 20b are depicted as substantially overlapping one and the other. Thepresent invention, however, is not so limited. As depicted in FIG. 6, asecurably joined region or weld 20 a is longitudinally offset from asecurably joined region or weld 20 b. Desirably, the length of thesecurably joined regions or welds 20 a and 20 b are substantiallysimilar. Also desirably, a portion of a securably joined region or weld20 a overlaps a portion of a securably joined region or weld 20 b. Suchoffsetting and/or overlapping of the securably joined regions or weldsprovide greater fatigue life. For example, the offset and overlappingwelds 20 a and 20 b of FIG. 6 surpassed 500,000 cycles of stentcontraction and/or expansion without fatigue failure. Similar welds thatare not offset and overlapping do not pass such fatigue testing.

Useful welding methods include, but are not limited to, laser welding,electron beam welding, resistance welding, tungsten inert gas welding,metal inert gas welding and combinations thereof. In laser and electronbeam welding the wires are partially melted by the energy provided bythe laser or electron beam. In gas tungsten arc welding (GTAW or TIGwelding), an arc is formed between an electrode, typically tungsten, andthe metal being welded. In metal inert gas (MIG) welding, an arc isgenerated between a filler electrode and the metal being welded withmetal melted from the filler electrode being added to the metal beingwelded. Resistance welding uses the application of electric current andsometimes mechanical pressure to create a weld between two pieces ofmetal. The weld areas may be shielded with an inert gas. Suitable, butnon-limiting, inert gasses include argon and argon/gas admixtures, suchas argon/hydrogen or argon/helium.

The wires or filaments 18 are made from a biocompatible material orbiocompatible materials. Useful biocompatible materials includebiocompatible metals, biocompatible alloys and biocompatible polymericmaterials, including synthetic biocompatible polymeric materials andbioabsorbable or biodegradable polymeric materials. Desirably, the wires18 are biocompatible metals or alloys made from, but not limited to,nitinol, stainless steel, cobalt-based alloy such as Elgiloy, platinum,gold, titanium, tantalum, niobium, polymeric materials and combinationsthereof. Useful synthetic biocompatible polymeric materials include, butare not limited to, polyesters, including polyethylene terephthalate(PET) polyesters, polypropylenes, polyethylenes, polyurethanes,polyolefins, polyvinyls, polymethylacetates, polyamides, naphthalanedicarboxylene derivatives, silks and polytetrafluoroethylenes. Thepolymeric materials may further include a metallic, a glass, ceramic orcarbon constituent or fiber. Useful and nonlimiting examples ofbioabsorbable or biodegradable polymeric materials includepoly(L-lactide) (PLLA), poly(D,L-lactide) (PLA), poly(glycolide) (PGA),poly(L-lactide-co-D,L-lactide) (PLLA/PLA), poly(L-lactide-co-glycolide)(PLLA/PGA), poly(D,L-lactide-co-glycolide) (PLA/PGA),poly(glycolide-co-trimethylene carbonate) (PGA/PTMC), polydioxanone(PDS), Polycaprolactone (PCL), polyhydroxybutyrate (PHBT),poly(phosphazene) poly(D,L-lactide-co-caprolactone) PLA/PCL),poly(glycolide-co-caprolactone) (PGA/PCL), poly(phosphate ester) and thelike. Wires made from polymeric materials may also include radiopaquematerials, such as metallic-based powders or ceramic-based powders,particulates or pastes which may be incorporated into the polymericmaterial. For example, the radiopaque material may be blended with thepolymer composition from which the polymeric wire is formed, andsubsequently fashioned into the stent as described herein.Alternatively, the radiopaque material may be applied to the surface ofthe metal or polymer stent. In either embodiment, various radiopaquematerials and their salts and derivatives may be used including, withoutlimitation, bismuth, barium and its salts such as barium sulfate,tantalum, tungsten, gold, platinum and titanium, to name a few.Additional useful radiopaque materials may be found in U.S. Pat. No.6,626,936, which is herein incorporated in its entirely by reference.Metallic complexes useful as radiopaque materials are also contemplated.The stent may be selectively made radiopaque at desired areas along thewire or made be fully radiopaque, depending on the desired end-productand application. Further, the wires 18 have an inner core of tantalum,gold, platinum, iridium or combination of thereof and an outer member orlayer of nitinol to provide a composite wire for improved radiocapicityor visibility. Desirably, the inner core is platinum and the outer layeris nitinol. More desirably, the inner core of platinum represents aboutat least 10% of the wire based on the overall cross-sectionalpercentage. Moreover, nitinol that has not been treated for shape memorysuch as by heating, shaping and cooling the nitinol at its martensiticand austenitic phases, is also useful as the outer layer. Furtherdetails of such composite wires may be found in U.S. Patent ApplicationPublication 2002/0035396 A1, the contents of which is incorporatedherein by reference. Preferably, the wires 18 are made from nitinol, ora composite wire having a central core of platinum and an outer layer ofnitinol. Further, the filling weld material, if required by weldingprocesses such as MIG, may also be made from nitinol, stainless steel,cobalt-based alloy such as Elgiloy, platinum, gold, titanium, tantalum,niobium, and combinations thereof, preferably nitinol. The material ofthe cathode is no critical and can be made out of any suitable metal.The filling weld material, when present, and the wire 18 may be made ofthe same material, for example nitinol. The filling weld material, whenpresent, may also be fully or partially radiopaque through use of thebelow-described materials.

As depicted in FIG. 3, stent 10′ is a braided stent having atraumaticends 12, 14. The stent includes filaments or wires 18 that are fully orpartially composite filaments or wires 18 to enhance visibility of thewires to provide improved external imaging of the wires in the body.Desirably, the enhanced visibility is enhanced radiopacity to provideimproved fluoroscopic or x-ray visualization of said wires in the body.Enhanced radiopacity may be achieved by using the above-describedradiopaque materials in combination with a biocompatible stent material.Such radiopaque materials are believed to be more visible underfluoroscopic or x-ray visualization due to their higher density than thecorresponding biocompatible stent material. The present invention,however, is not limited to a stent with improved fluoroscopic or x-rayvisualization. For example, the stent 10′ may also have improvedexternal imaging under magnetic resonance imaging (MRI) and/orultrasonic visualization techniques. Magnetic resonance imaging isproduced by complex interactions of magnetic and radio frequency fields.Materials for enhancing MRI visibility include, but not be limited to,metal particles of gadolinium, iron, cobalt, nickel, dysprosium,dysprosium oxide, platinum, palladium, cobalt based alloys, iron basedalloys, stainless steels, or other paramagnetic or ferromagnetic metals,gadolinium salts, gadolinium complexes, gadopentetate dimeglumine,compounds of copper, nickel, manganese, chromium, dysprosium andgadolinium. To enhance the visibility under ultrasonic visualization thestent 10′ of the present invention may include ultrasound resonantmaterial, such as but not limited to gold.

The stent wires 18 at the open end 14 are bent to form closed loop ends15 thereat. As depicted in FIG. 3, the loop ends 15 are substantiallyangular having approximately or about a 90° bend. The radius ofcurvature at the point of the bend is desirably minimized. In otherwords, the loop end 15 desirably has an angularly bent portion betweensubstantially straight wire portions that do not otherwise have aportion with a significant radius of curvature. The loop ends 15,however, are not limited to angular bends of 90° and other bend anglesmay suitably be used. For example, angular bends with a bend angle fromabout 30° to about 150° are also useful. Other useful bend anglesinclude from about 60° to about 120°, from about 70° to about 110°, fromabout 80° to about 100°, from about 85° to about 95°, and the like.

The loop ends 15, however, are not limited to substantially angularbend-containing loops and other shaped loop ends, such as semi-circular,semi-elliptical and other smoothly curved or substantially smoothlycurved loops, including but not limited to cathedral-shaped loops, maysuitably be used.

Thus, in one desirable aspect of the present invention, a stent isprovided with opposed atraumatic, closed-looped ends. One of theatraumatic ends may include closed loops having substantially angularbends, as described above, and the other opposed atraumatic end mayinclude a cathedral type arch or loop, as described below.

As depicted in FIGS. 7-11, certain stent wires 56, 62 may be extendedbeyond adjacent wires 50, 64, and then looped back to proximal wires 52,60 and 58, 64, respectively. Adjacent portions of wires 50 and 56 areabuttingly disposed at juxtaposed region 68. Similarly, adjacentportions of wires 52 and 60 and the adjacent portion of the extendedloop portion 66 are juxtaposingly disposed at abutting region 70;adjacent portions of wires 54 and 62 are juxtaposingly disposed atjuxtaposed region 72; and adjacent portions of wires 58 and 64 and theadjacent portion of the extended loop portion 67 are juxtaposinglydisposed at juxtaposed region 74. Desirably, the juxtaposingly disposedwire portions in the juxtaposed regions are substantially parallel toone and the other, for example, but not limited to, being within aboutplus or minus 10 degrees of parallelism to one and the other,preferably, but not limited to within about plus or minus 5 degrees ofparallelism. As used herein the term “juxtaposed” and its variants referto wires that are proximal to one and the other, desirably in touchingrelationship. The wires may be in a side-to-side relationship, anend-to-end relationship, a crossing over relationship, a buttingrelationship, and the like.

As depicted in FIG. 7, the wires at the juxtaposed regions 68, 70, 72,74 may be secured by welds 76. Desirably, welds 76 are offset andoverlapping pair of welds as described above. The present invention,however, is not limited to the welding of the longitudinally disposedwire portions as depicted in FIGS. 7-8. For example, as depicted in FIG.33, a weld joint 200 may securably join juxtaposed wires 202 and 204which form an in integral part of the braid. Desirably, the weld joint200 is positioned inside the adjacent loop, i.e., after adjacent wirescross, to provide higher radial strength and to withstand higher radialcompression forces.

Desirably, the extended loop portions 66, 67 are of an arch withequilateral sides' design, which can be referred to as a cathedral typeof arch or loop. As depicted in FIG. 9, the equilaterally arched loop 78has an apex or vertex 80. As used herein, the term “vertex” and itsvariants refer to the intersection of two geometric lines or curves. Asused herein, the term “apex” and its variants refer to a vertex at thetop or summit of a loop. Desirably, the equilaterally arched loop 78does not have any bends, which are defined as areas having dissimilarcurvatures on either side of a point, except for the apex 80. In otherwords, the equilaterally arched loop 78 has an apex, but not other sharpbends. Desirably, the equilaterally arched loop 78 has one vertex (orapex 80) having similar curvatures on either side of the one vertex (orapex 80), but does not contain a second vertex having dissimilarcurvatures on either side of the second vertex.

The equilaterally arched loop design offers several advantages,including reduced deployment force, as compared to loop designs having aplurality of vertices or sharp bends. When a stent is constrained on orin a delivery system (not shown), the multiple sharp bends in the endloops of the stent typically impinge on the wall of the delivery systemand become slightly imbedded thereat, thereby distorting the outersheath of the delivery system. This results in significantly greaterdeployment force values. Further, as the equilaterally arched loop hasonly one sharp bend, i.e., its apex, and is defined otherwise by agradual curvature, the gradual curvature portions do not become imbeddedin the wall of the delivery system, thereby significantly reducing theresultant deployment force.

In another aspect of the present invention as depicted in FIGS. 10 and11, an equilaterally arched loop 82 may have an apex 84 and vertices 86having substantially straight line portions 88. In such a case, thevertices 86 and the straight line portions 88 have low profile welds 90there over to adjoin other adjacently abutting stent wires (not shown).The equilaterally arched loops 66, 67, 78, 82 of the present inventionmay be suitably formed by winding their stent wires about shaped pins 98on a mandrel 100 as depicted in FIG. 13. Further details of thecathedral type of arch or closed-loop configuration may be found in U.S.application Ser. No. 10/845,844, filed May 15, 2004, the contents ofwhich are incorporated herein by reference.

Further, either or both of the ends 12, 14 of the stent 10, 10′,including end 12 with equilaterally arched loops 66, 67, 78, 82, mayhave a suture or sutures attached thereto. Such sutures, which may betextile, polymeric or metallic, are useful for positioning,repositioning, and/or removing the stent 10, 10′. Useful polymericmaterials include polyester, such as braidedpolytetrafluoroethylene-impregnated polyesters. As depicted in FIG. 32,a suture loop 150 may be disposed at the either or both ends 12, 14 ofthe stent 10, 10′. Desirably, the suture loop 150 is disposed at the end12. As depicted in FIG. 32, the suture loop 150 is looped among the loopportions, such as portions 66, 67, 78 or 82, of the stent 10, 10′. Thesuture loop 150 may be used by a practitioner for re-positioning and/orremoving the stent 10, 10′. The suture loop 150 may be grabbed bysuitable forceps, such as rat-tooth forceps (not shown). Upon grabbingthe suture loop 150 and applying a pulling force thereto, the sutureloop 150 cinches and contracts the end 12 or 14 of the stent 10, 10′,thereby easing movement of the stent 10, 10′ in vivo. The suture loopmay be relatively taut over the stent end of may be loosely disposedthereat so as to have some slack. The suture loop 150 is a closed-loopdevice where the ends of the thread or strand forming the suture loopare securably joined together by, for example, tying, gluing and/orfusing the end together. Ultrasonic fusing of polymeric suture thread,in particular knots formed in the thread, is also useful with thepresent invention. Further details of suitable fused suture knots may befound in U.S. patent application Ser. No. 11/073,779, filed Mar. 7,2005, the contents of which are incorporated herein by reference. Thepresent invention is not so limited and other designs useful forpositioning, repositioning, and/or removing stent 10 may suitably beused. Further details of such other positioning and/or repositioningdesigns may be found in U.S. application Ser. No. 10/845,844, filed May15, 2004, which published as U.S. Patent Application Publication No.2005/0209639 A1, the contents of all of which are incorporated herein byreference. Further, a retrieval and/or repositioning loop may beintegrally formed into the braided stent structure. Such an integralretrieval and/or repositioning loop includes at least of two wiresformed into the repositioning and/or retrieval loop which has anelongated portion circumferentially disposed at the end of the stent.The reposition and/or retrieval loop includes two sections which runadjacent to each other prior to crossing to permit grabbing of bothsections simultaneously by a practitioner. Further details of such areposition and/or retrieval loop may be found in U.S. ProvisionalApplication No. 60/680,689, titled “Integrated Stent Repositioning andRetrieval Loop”, filed May 13, 2005, the contents of which areincorporated herein by reference.

Moreover, the repositioning and/or retrieval of the stent 10, 10′ mayalso be accomplished without the use of the above-described suture loop150 and/or the integral loop. For example, a repositioning and/orretrieval device (not shown), such as a catheter, endoscope or the like,may incorporate grabbing detents which may directly engage the loops 66,67, 78, 82 of the stent 10, 10′. Such a repositioning and/or retrievaldevice may also be able to radially compress the stent 10, 10′ at theloop ends 66, 67, 78, 82 to facilitate repositioning and/or retrieval ofa deployed stent, for example by withdrawing the stent 10, 10′ into alumen of the repositioning and/or retrieval device. A stent restrainingdevice, such as a polymeric sleeve, may be positioned within the lumenof the repositioning and/or retrieval device to secure the stent thereinduring repositioning and/or retrieval. Further, the lumen need not be asubstantially cylindrical lumen, and it may have a conical portion, forexample in the shape of a funnel, which may be useful for transitioningthe stent 10, 10′ from it deployed diameter to a smaller diameter forsecurement within the lumen of the repositioning and/or retrievaldevice.

In one embodiment of the present invention, one end of the stent mayhave weld joints which, due to their positioning, provide higher radialstrength, i.e., the resultant stents can withstand higher radialcompressive forces without fear of weld failure. In these embodiments,the weld joint 20 a, 20 b may be positioned between the crossings ofadjacent wires 18 a, 18 b, 18 c, as shown in FIGS. 4-6.

In another aspect of the present invention, the loop ends at the openend 14 of the stent 10 may be longitudinally staggered or offset fromone and the other. Desirably, each loop 15 is staggered in alternativelong and short longitudinally extending loops. Such a staggering oroffsetting of the loop ends 15 reduces deployment forces for delivery ofthe stent. By longitudinally staggering or offsetting the length and thealignment of the loop ends 15, the force required to deliver the stent10 to an intended bodily site is reduced as compared to a stent nothaving a staggered loop end.

When a stent is tightly constrained in a delivery system, each loopextends to exert a force on a wall of the delivery system, possiblyembedding itself into the wall to some extent. When the loops arelongitudinally staggered, the force exerted by each loop is laterallydistributed in a more even fashion. Such staggering reduces the forcerequired to move the stent from the wall of the delivery system, therebyreducing the overall deployment force. In addition, staggered loops areless likely to interfere with each other as compared to non-staggeredloops, again reducing the deployment force. In other words, staggeredloops will less likely impede the delivery of the stent as compared tonon-staggered loops.

As depicted in FIG. 12, which is a partial exploded view of a portion ofthe stent end 14 of FIG. 3, stent loops 15 a are staggered from stentloops 15 b. The staggering of the loops results in a longitudinaloffset, d, between the apexes or apices of the adjacent loops. Asdepicted in FIG. 12, one set of loops 15 a are offset from another setof loops 15 b by a single longitudinal offset, d. The present invention,however, is not so limited. For example, the stent end 14 may havestaggered loop ends having more than one or a plurality of longitudinaloffsets. The staggered loop ends 15 a, 15 b with either a single offsetor a plurality of offsets may suitably be formed by providing a mandrelwith longitudinally offset pins (not shown) and commencing braiding orotherwise positioning the stent wires thereat.

As depicted in FIG. 14, the stent 10 may be fully, substantially orpartially covered with a polymeric material 102. The covering may be inthe form of a tubular structure. One nonlimiting example of a polymericmaterial is silicone. The polymeric material and/or silicone 102 may bedisposed on external surfaces 104 of the stent 10, as depicted in FIG.15, or disposed on the internal surfaces 106 of the stent 10, asdepicted in FIG. 16, or combinations thereof. The silicone covering maybe suitably formed by dip coating the stent. Details of such dip coatingmay be found in U.S. Pat. No. 5,875,448, the content of which isincorporated herein by reference. The present invention is not limitedto forming the silicone film by dip coating, and other techniques, suchas spraying, may suitably be used. After applying the silicone coatingor film to the stent, the silicone may be cured. Desirably, the curingis low temperature curing, for example from about room temperature toabout 90° C. for a short period of time, for example from about 10minutes or more to about 16 hours. The cured silicone covering may alsobe sterilized by electronic beam radiation, gamma radiation ethyleneoxide treatment and the like. Further details of the curing and/orsterilization techniques may be found in U.S. Pat. No. 6,099,562, thecontent of which is incorporated herein by reference. Argon plasmatreatment of the cured silicone may also be used. Argon plasma treatmentof the cured silicone modifies the surface to the cured silicone to,among other things, make the surface less sticky.

With any embodiment of the stent 10, 10′, 128 is usable to maintainpatency of a bodily vessel, such as in the coronary or peripheralvasculature, esophagus, trachea, bronchi colon, biliary tract, urinarytract, prostate, brain, and the like. Also, the stent 10, 10′ may betreated with any of the following: anti-thrombogenic agents (such asheparin, heparin derivatives, urokinase, and PPack (dextrophenylalanineproline arginine chloromethylketone); anti-proliferative agents (such asenoxaparin, angiopeptin, or monoclonal antibodies capable of blockingsmooth muscle cell proliferation, hirudin, and acetylsalicylic acid);anti-inflammatory agents (such as dexamethasone, prednisolone,corticosterone, budesonide, estrogen, sulfasalazine, and mesalamine);antineoplastic/antiproliferative/anti-miotic agents (such as paclitaxel,5-fluorouracil, cisplatin, vinblastine, vincristine, epothilones,endostatin, angiostatin and thymidine kinase inhibitors); anestheticagents (such as lidocaine, bupivacaine, and ropivacaine);anti-coagulants (such as D-Phe-Pro-Arg chloromethyl keton, an RGDpeptide-containing compound, heparin, antithrombin compounds, plateletreceptor antagonists, anti-thrombin antibodies, anti-platelet receptorantibodies, aspirin, prostaglandin inhibitors, platelet inhibitors andtick antiplatelet peptides); vascular cell growth promotors (such asgrowth factor inhibitors, growth factor receptor antagonists,transcriptional activators, and translational promotors); vascular cellgrowth inhibitors (such as growth factor inhibitors, growth factorreceptor antagonists, transcriptional repressors, translationalrepressors, replication inhibitors, inhibitory antibodies, antibodiesdirected against growth factors, bifunctional molecules consisting of agrowth factor and a cytotoxin, bifunctional molecules consisting of anantibody and a cytotoxin); cholesterol-lowering agents; vasodilatingagents; and agents which interfere with endogenous vasoactivemechanisms.

Further, with any embodiment of the stent 10, 10′ the general tubularshape may be varied. For example, the tubular shape may have a varieddiameter, an inwardly flared end, an outwardly flared end and the like.Further, the ends of the stent may have a larger diameter than themiddle regions of the stent. A braided stent with outwardly flared endsis further described in U.S. Pat. No. 5,876,448, the contents of whichare incorporated herein by reference.

In another aspect of the present invention, a stent delivery anddeployment system is provided. As depicted in FIGS. 17-22, a stentdelivery and deployment system 120 is provided. The system 120 includesa catheter 122 having a distal end 124 and a proximal end 126; a stent128 having a distal end 130 and a proximal end 132; a retractable sheath134 having a distal end 136 and a proximal end 138; a marker band 140disposed at the distal end 136 of the delivery sheath 134; and apost-deployment marker band 142 disposed on an inner member 144 of thecatheter 122 toward the proximal end 126 of the catheter 122;interrelated as shown. The marker band 140 may be placed at the distalend 136 of the sheath 134. FIGS. 17 and 20 depict a partially deployedstent 128. Prior deployment sheath 134 substantially covers or evenextends beyond the distal end 130 of the stent 128. The marker band 140is disposed to overlap the distal end 130 of the stent 128 in thepre-deployment stage. Typical prior art systems have a marker bandpositioned on the sheath, but beyond the stent, which complicates stentplacement. Another reason for such marker placement 140 overlapping thestent 128 is for constraining the stent 128 prior to deployment. Withoutthe marker band 140 placed at the distal location of the stent, thestent may expand into the polymeric sheath during sterilization and/orstorage. Such expansion induces higher frictional forces at thislocation, ultimately increasing the deployment force required to deploythe stent. When a marker band does not overlap the stent, deploymentforces in the range of about 14 pounds-force is required. The system 120of the present invention requires significantly less deployment force,approximately in the range of about 5 to about 6 pounds-force.Desirably, deployment forces with the system 120 of the presentinvention are less than about 10 pounds-force, more desirably less thanabout 8 pounds-force, preferably less than about 7 pounds-force or less.

The system 120 of the present invention a post-deployment marker band142 disposed on an inner member 144 of the catheter 122 toward theproximal end 126 of the catheter 122. For delivery of the stent 128, thepost-deployment marker band 142 is placed proximally or before thestricture or damaged vessel site 146. Such placement ensures that thestent 128 will always completely span the vessel site 146 even when thestent 128 foreshortens as it expands during delivery. The stricture ordamaged vessel site 146 may suitably include bodily tissue, bodilyorgans, vascular lumens, non-vascular lumens and combinations thereof,such as, but not limited to, in the coronary or peripheral vasculature,esophagus, trachea, bronchi, colon, biliary tract, urinary tract,prostate, brain, stomach and the like

The markers 140 and 142 may comprise any useful radiopaque material ormaterials including any metal or plastics being radiopaque or capable ofbeing impregnated with radiopaque materials. Useful radiopaque materialsinclude, but are not limited to gold, barium sulfate, ferriticparticles, platinum, platinum-tungsten, palladium, platinum-iridium,rhodium, tantalum or combinations thereof. The sheath 134 may compriseany plastic or polymeric material, desirably a somewhat hard butflexible plastic or polymeric material. The sheath 134 may betransparent or translucent, desirably substantially or partiallytransparent. Furthermore, the sheath 134 may be constructed of anysuitable biocompatible materials, such as, but not limited to, polymersand polymeric materials, including fillers such as metals, carbonfibers, glass fibers or ceramics. Useful sheath materials include, butare not limited, polyethylene, polypropylene, polyvinyl chloride,polytetrafluoroethylene, including expanded polytetrafluoroethylene(ePTFE), fluorinated ethylene propylene, fluorinated ethylene propylene,polyvinyl acetate, polystyrene, poly(ethylene terephthalate),naphthalene dicarboxylate derivatives, such as polyethylene naphthalate,polybutylene naphthalate, polytrimethylene naphthalate andtrimethylenediol naphthalate, polyurethane, polyurea, silicone rubbers,polyamides, polyimides, polycarbonates, polyaldehydes, polyether etherketone, natural rubbers, polyester copolymers, styrene-butadienecopolymers, polyethers, such as fully or partially halogenatedpolyethers, and copolymers and combinations thereof.

It may be noted that FIGS. 17 and 20 depict a partially deployed stent128. FIGS. 18 and 21 depict a colonically deployed stent with theenlarged stent portion 130 being distal to the site 146. FIGS. 19 and 22depict a duodenally deployed stent with the enlarged stent portion 132being proximal to the site 146.

FIGS. 23-31 depict additional details of the arrangement of the marker140 with the system 120 of the present invention. As depicted in FIG.23, the marker 140 is disposed between the sheath 134 and the stent 128at the distal end 136 of the sheath 134 with the marker 140 being placedproximal to the distal end 130 of the stent 128. Although the distal end136 of the sheath 134 is depicted as covering and extending beyond thedistal end 130 of the stent 128, the present invention is not solimited. The distal end 136 of the sheath 134 may be flush orsubstantially flush with the distal end 130 of the stent 128 (notshown). FIG. 24 is a cross-sectional view of the system 120 taken alongthe 23-23 axis. As depicted in FIG. 24 the sheath 134, the stent 128 andthe marker 140 are continuous tubular or cylindrical members. Thepresent invention, however, is not so limited. For example, the marker140 need not be a continuous tubular member, but may be, for example, asegmented member.

As depicted in FIG. 26, the marker 140 may be disposed over the outsidesurface or exterior portion of the sheath 134. As depicted in FIGS. 25and 26 the marker 140 may be adjacently disposed, includingsubstantially disposed, to or over the distal end 130 of the stent 128.

FIGS. 28-31 depict alternate embodiments of the placement of the marker140 with the sheath 134. As depicted in FIG. 28, the marker 140 may befully embedded within the sheath 134. As depicted in FIG. 29, the marker140 may interrupt or partially interrupt the sheath 134. As depicted inFIG. 30, the marker may be partially embedded within the sheath 134, butbeing exposed at the interior or luminal surface of the sheath 134,which is generally depicted as the bottom portion of the sheath 134 inFIG. 30. As depicted in FIG. 31, the marker may be partially embeddedwithin the sheath 134, but being exposed at the exterior surface of thesheath 134, which is generally depicted as the upper portion of thesheath 134 in FIG. 30.

In one aspect of the present invention, an implantable stent isprovided. The stent includes a plurality of elongate wires braided toform a hollow tubular structure having a tubular wall to define aninterior surface and an exterior surface and having opposed open firstand second ends, wherein the opposed open first and second ends areatraumatic ends, and further wherein the wires include composite wiresto enhance visibility of the wires to provide improved external imagingof the wires in the body. Desirably, the enhanced visibility is enhancedradiopacity and the external imaging is fluoroscopic or x-rayvisualization.

The atraumatic ends of the stent are desirably free of any loose wireends.

The elongate composite wires of the stent may be metallic wires havingan outer metallic portion including a first metal and an inner metalliccore portion including a second metal, wherein the first metal isdifferent from the second metal. Desirably, the second metal of theinner core includes a radiopaque material selected from gold, bariumsulfate, ferritic particles, platinum, platinum-tungsten, palladium,platinum-iridium, rhodium, tantalum or combinations thereof. The firstmetal of the outer portion may include nitinol.

The stent of this aspect of the present invention desirably may alsohave wires that terminate at the second end, wherein the wires at thefirst end are arranged in a series of closed loops with each loop havingan apex defined by a bend in one of the wires and having an opposed basedefined by crossing of adjacent wires, and further wherein the apex ofadjacent closed loops are longitudinally offset from one and the other.

The stent of this aspect of the present invention desirably may alsohave wires that terminate at the second open end, and adjacentlyjuxtaposed wires are securably joined at the second open end to providefirst securably joined regions, wherein at least one of the adjacentlyjuxtaposed stent wires are extended past the first securably joinedregions and further wherein the extended and looped wire is securablyjoined to the proximal pair of wires with second securably joinedregions to define closed loop wire ends. Desirably, the wires aresecurably joined by welding the wired and further wherein the securablyjoined regions are welds.

The stent of this aspect of the present invention desirably may alsohave wires that terminate at the second open end, and further whereinadjacently juxtaposed wires at the second open end are securably joinedto provide securably joined regions, wherein ends of the terminatedwires are smoothed to remove sharp edges from the wire ends. Desirably,the wires are securably joined by welding the wired and further whereinthe securably joined regions are welds.

The stent of this aspect of the present invention desirably may alsohave wires that terminate at the second open end, and adjacentlyjuxtaposed wires are securably joined at the second open end to providefirst securably joined regions, wherein at least one of the adjacentlyjuxtaposed stent wires are extended past the first securably joinedregions and looped such that the extended end abuts a proximal pair ofstent wires; and further wherein the extended and looped wire issecurably joined to the proximal pair of wires with second securablyjoined regions which are longitudinally offset from the first securablyjoined regions. Desirably, the wires are securably joined by welding thewired and further wherein the securably joined regions are welds. Thefirst and the second welds may have a substantially same longitudinallyextending extend. The first and the second welds may have longitudinallyextending portions which overlap one and the other.

The stent of this aspect of the present invention may also be partiallyor fully coated with a polymeric material. The stent may further includehollow tubular graft disposed partially or fully over the interior orthe exterior surface. Desirably, the graft is a polymeric material. Thepolymeric material may be selected from polyester, polypropylene,polyethylene, polyurethane, polynaphthalene, polytetrafluoroethylene,expanded polytetrafluoroethylene, silicone, and combinations thereof.

In another aspect of the present invention, a method for making animplantable stent is provided. The method includes the steps of (i)providing a plurality of elongate wires, wherein the elongate wiresinclude composite wires to enhance visibility of the wires to provideimproved external imaging of the wires in the body; and (ii) braidingthe wires to form a hollow tubular structure having a tubular wall todefine an interior surface and an exterior surface and having opposedopen first and second ends, wherein the opposed open first and secondends are atraumatic ends. Desirably, the enhanced visibility is enhancedradiopacity and the external imaging is fluoroscopic or x-rayvisualization.

The method this aspect of the present invention may further include thestep of arranging the wires at the first end in a series of closed loopswith each loop having an apex defined by a bend in one of the wires andhaving an opposed base defined by crossing of adjacent wires, whereinthe apex of adjacent closed loops are longitudinally offset from one andthe other.

The method this aspect of the present invention may also further includethe steps of terminating the wires at the second end; aligning the wiresat the second end into a plurality of mated adjacent wires to define aplurality of juxtaposed regions; and securably joining the matedadjacent wires to one and the other at the juxtaposed regions to definea closed loop at the second end. Desirably, the step of securablyjoining the wires includes welding the wires.

The method this aspect of the present invention may further include thesteps of terminating the wires at the second end to form terminated wireends; aligning the wires at the second end into a plurality of matedadjacent wires to define a plurality of juxtaposed regions; securablyjoining the mated adjacent wires to one and the other at the juxtaposedregions to define a plurality of securably joined regions; and smoothingthe terminated wire ends by removing sharp edges from the wire ends.Desirably, the step of securably joining the wires includes welding thewires, and further wherein the securably joined regions are welds.

The method this aspect of the present invention may further include thesteps of terminating the wires at the second end; aligning the wires atthe second end into a plurality of mated adjacent wires to define aplurality of juxtaposed regions; extending at least one of the matedstent wires to provide an extended stent wire; looping the extendedstent wire so the extended end abuts a proximal pair of stent wires;securably joining the mated adjacent wires to one and the other at thejuxtaposed regions; and securably joining the extended and looped wireto the proximal pair of wires with a pair of longitudinally offsetsecurably joined regions. Desirably, the step of securably joining thewires includes welding the wires, and further wherein the securablyjoined regions are welds.

In another aspect of the present invention, a stent delivery anddeployment system is provided. The system includes a delivery catheterhaving a distal end; an elongate radially self-expanding stent having adistal end adjacent the distal end of the catheter; an elongate sheathretractably positioned about the stent so as to maintain the stent in aradially compressed delivery condition about the distal end of thecatheter; and a retaining band positioned adjacent the distal end of thestent, the retaining band being retractable with the sheath so as toallow longitudinally progressive and radial expansion of the stent uponthe retraction of the sheath for deploying the stent. The retaining bandmay include a radiopaque marker. The band may also be formed of aradiopaque material.

In yet another aspect of the present invention, a method of deliveringand deploying an expandable stent includes the steps of disposing aradially expanding stent at a distal end of a delivery catheter;positioning a retractable sheath having a retaining band adjacent adistal end of the stent over the stent so as to maintain the stent in aradially compressed delivery condition; and retracting the sheath andthe retaining band with respect to the distal end of the catheter toallow longitudinal progressive expansion of the stent. The sheath andthe band are retracted together. The retaining band may include aradiopaque marker or is formed of a radiopaque material. The positioningstep may further include the step of positioning the band at the distalend of the stent. Desirably, the stent is a braided stent having opposedfirst and second atraumatic open ends.

In one aspect of the present invention, a method for making animplantable stent includes the steps of (i) providing a plurality ofelongate stent wires; (ii) forming the wires into a hollow tubularstructure having opposed first and second open ends; (iii) terminatingthe wires at the second end to form terminated wire ends; (iii) aligningthe wires at the second end into a plurality of mated adjacent wires todefine a plurality of juxtaposed regions; (iv) welding the matedadjacent wires to one and the other at the juxtaposed regions to definea plurality of welds; and (v) smoothing the terminated wire ends byremoving sharp edges from the wire ends. The step of smoothing theterminated wire ends may further include removing a portion of wirematerial at the terminated wire end to provide a diagonally extendingportion at the wire end; removing a portion of wire material at theterminated wire end to provide a curved portion at the wire end; heatingthe terminated wire end to partially melt wire material at the wire end;and combinations thereof. Desirably, the step of heating includespassing a laser beam over the terminated wire end.

The method of this aspect of the present invention claim 1 may furtherinclude the steps of chemically or electro-chemically removing a portionof the welds; chemically or electro-chemically removing a portion of theterminated wire ends and combinations thereof.

The method of this aspect of the present invention of claim 1 mayinclude forming the tubular structure by braiding the wires, winding thewires, knitting the wires, and combinations thereof.

The method of this aspect of the present invention claim 1 may include awire including a radiopaque material. The elongate wires may includebiocompatible materials selected from the group consisting of nitinol,cobalt-based alloy, stainless steel, platinum, gold, titanium, tantalum,niobium, polymeric materials and combinations thereof, desirably,nitinol. Further, the elongate wires may be composite wires for improvedradiopacity, such as wires having an inner core radiopaque materialselected from the group consisting of gold, barium sulfate, ferriticparticles, platinum, platinum-tungsten, palladium, platinum-iridium,rhodium, tantalum or combinations thereof and an outer portion ofnitinol.

In another aspect of the present invention, an implantable stentincludes a plurality of wires arranged to form a hollow tubularstructure having a tubular wall to define an interior surface and anexterior surface and having opposed open first and second ends, whereinthe wires terminate at the second open end and adjacently juxtaposedwires are welded at the second open end with a welding material toprovide welds, and further wherein ends of the terminated wires aresmoothed to remove sharp edges from the wire ends and to provide alongitudinally extending wire portion at the wire ends. Thelongitudinally extending wire portion at the wire ends may include adiagonally extending portion at the wire end, may include a curvedportion at the wire end, may include partially melt wire material at thewire end, and combinations thereof.

The stent of this aspect of the present invention may include wiresincluding a biocompatible material selected from the group consisting ofnitinol, stainless steel, cobalt-based alloy, platinum, gold, titanium,tantalum, niobium, polymeric materials and combinations thereof and anouter portion of nitinol. The weld material and the wire material may benitinol. The elongate wires have an inner core radiopaque materialselected from the group consisting of gold, barium sulfate, ferriticparticles, platinum, platinum-tungsten, palladium, platinum-iridium,rhodium, tantalum or combinations thereof and an outer portion ofnitinol.

The stent of this aspect of the present invention may include a coatedor partially coated stent wherein the stent is coated with a polymericmaterial. The stent may be is partially or fully covered with abiologically active material which is elutably disposed with thepolymeric material.

The stent of this aspect of the present invention may further include ahollow tubular graft disposed over the interior or the exterior surface.The graft may be a polymeric material, such as polyester, polypropylene,polyethylene, polyurethane, polynaphthalene, polytetrafluoroethylene,expanded polytetrafluoroethylene, silicone, and combinations thereof.

Desirably, the stent of this aspect of the present invention is abraided stent.

In another aspect of the resent invention, a method for making animplantable stent including (i) providing a plurality of elongate stentwires; forming the wires into a hollow tubular structure having opposedfirst and second open ends; terminating the wires at the second end;aligning the wires at the second end into a plurality of mated adjacentwires to define a plurality of juxtaposed regions; and extending atleast one of the mated stent wires to provide an extended stent wire;looping the extended stent wire so the extended end abuts a proximalpair of stent wires; welding the mated adjacent wires to one and theother at the juxtaposed regions; and welding the extended and loopedwire to the proximal pair of wires with a pair of longitudinally offsetwelds. The pair of longitudinally offset welds may have a substantiallysame longitudinally extending extend, may have a portion which overlapone and the other, or combinations thereof.

The step of forming the tubular structure may include braiding thewires, winding the wires, knitting the wires, and combinations thereof.The wire may include a radiopaque material. The elongate wires mayinclude biocompatible materials selected from the group consisting ofnitinol, cobalt-based alloy, stainless steel, platinum, gold, titanium,tantalum, niobium, polymeric materials and combinations thereof,desirably nitinol. The elongate wires may be composite wires forimproved radiopacity. The elongate wires may have an inner coreradiopaque material selected from the group consisting of gold, bariumsulfate, ferritic particles, platinum, platinum-tungsten, palladium,platinum-iridium, rhodium, tantalum or combinations and an outer portionof nitinol.

The step of welding may include welding selected from the groupconsisting of laser welding, electron beam welding resistance welding,tungsten inert gas welding, metal inert gas welding and combinationsthereof.

In another aspect of the present invention, an implantable stentincludes a plurality of wires arranged to form a hollow tubularstructure having a tubular wall to define an interior surface and anexterior surface and having opposed open first and second ends, whereinthe wires terminate at the second open end and adjacently juxtaposedwires are welded at the second open end with a welding material toprovide first welds, wherein at least one of the adjacently juxtaposedstent wires are extended past the welds and looped such that theextended end abuts a proximal pair of stent wires; and further whereinthe extended and looped wire is welded with a welding material to theproximal pair of wires with second welds which are longitudinally offsetfrom the first welds. The first and the second welds may have asubstantially same longitudinally extending extend, may have alongitudinally extending portions which overlap one and the other, orcombinations thereof.

The wires may include a biocompatible material selected from the groupconsisting of nitinol, stainless steel, cobalt-based alloy, platinum,gold, titanium, tantalum, niobium, polymeric materials and combinationsthereof. The weld material and the wire material may be nitinol. Theelongate wires may have an inner core radiopaque material selected fromthe group consisting of gold, barium sulfate, ferritic particles,platinum, platinum-tungsten, palladium, platinum-iridium, rhodium,tantalum or combinations thereof and an outer portion of nitinol.

The stent may be coated with a polymeric material. The stent may bepartially or fully covered with a biologically active material which iselutably disposed with the polymeric material. The stent may furtherinclude a hollow tubular graft disposed over the interior or theexterior surface. The graft may be a polymeric material, such as apolymeric material is selected from the group consisting of polyester,polypropylene, polyethylene, polyurethane, polynaphthalene,polytetrafluoroethylene, expanded polytetrafluoroethylene, silicone, andcombinations thereof.

Desirably, the stent is a braided stent.

In another aspect of the present invention, an implantable stentincludes a plurality of wires arranged to form a hollow tubularstructure having a tubular wall to define an interior surface and anexterior surface and having opposed open first and second ends, whereinthe wires at the first end are arranged in a series of closed loops witheach loop having an apex defined by a bend in one of the wires andhaving an opposed base defined by crossing of adjacent wires, whereinthe apex of adjacent closed loops are longitudinally offset from one andthe other. The closed loops may define geometric areas of substantiallythe same size, may have substantially similar geometric shapes andcombinations thereof. The adjacent bases of the closed loops may belongitudinally offset from one and the other, may not be substantiallylongitudinally offset from one and the other, and combinations thereof.

The loops may have a geometric pattern in a general diamond shape havingfour corners with the apex forming a top corner, the base forming anopposed bottom corner and opposed side corners defined by crossing ofadjacent wires which are different wires from those defining the basecorner. The opposed side corners of adjacent closed loops may belongitudinally offset from one and the other, may not be substantiallylongitudinally offset from one and the other or combinations thereof.Each of the apexes of the closed loops may be longitudinally positionedbeyond the opposed corner of any of the closed loops. Each of the apexesmay have an area of curvature and adjacent apexes are longitudinallyoffset by a longitudinal distance where the adjacent apexes of theclosed loops are longitudinally positioned within the area of curvatureof adjacent loops.

The wires may terminate at the second open end and adjacently juxtaposedwires are welded at the second open end with a welding material toprovide first welds, wherein at least one of the adjacently juxtaposedstent wires are extended past the welds and further wherein the extendedand looped wire is welded with a welding material to the proximal pairof wires with second welds to define closed loop wire ends. The closedloop wire ends at the second open end may have apexes where the apexesof adjacent closed loop wire ends are longitudinally offset from one andthe other. The second welds may be longitudinally offset from the firstwelds. The ends of the terminated wires may be smoothed by removingsharp edges from the wire ends.

The wires may include a biocompatible material selected from the groupconsisting of nitinol, stainless steel, cobalt-based alloy, platinum,gold, titanium, tantalum, niobium, polymeric materials and combinationsthereof and an outer portion of nitinol. The s weld material and thewire material may be nitinol. The elongate wires may have an inner coreradiopaque material selected from the group consisting of gold, bariumsulfate, ferritic particles, platinum, platinum-tungsten, palladium,platinum-iridium, rhodium, tantalum or combinations thereof and an outerportion of nitinol.

The stent may be coated with a polymeric material. The stent may bepartially or fully covered with a biologically active material which iselutably disposed with the polymeric material. A hollow tubular graftmay be disposed over the interior or the exterior surface. The graft maybe a polymeric material, such as a polymeric material is selected fromthe group consisting of polyester, polypropylene, polyethylene,polyurethane, polynaphthalene, polytetrafluoroethylene, expandedpolytetrafluoroethylene, silicone, and combinations thereof.

Desirably, the stent may be a braided stent.

In another aspect of the present invention, a method for making animplantable stent includes (i) providing a plurality of elongate stentwires; and (ii) forming the wires into a hollow tubular structure havingopposed first and second open ends, wherein the wires at the first endare arranged in a series of closed loops with each loop having an apexdefined by a bend in one of the wires and having an opposed base definedby crossing of adjacent wires, wherein the apex of adjacent closed loopsare longitudinally offset from one and the other. The method may furtherinclude the steps of (i) terminating the wires at the second end; (ii)aligning the wires at the second end into a plurality of mated adjacentwires to define a plurality of juxtaposed regions; and (iii) welding themated adjacent wires to one and the other at the juxtaposed regions todefine a closed loop at the second end. The adjacent closed loops at thesecond end may be longitudinally staggered from one and the other. Thestep of forming the tubular structure may include braiding the wires,winding the wires, knitting the wires, and combinations thereof.

The wire may include a radiopaque material. The elongate wires mayinclude biocompatible materials selected from the group consisting ofnitinol, cobalt-based alloy, stainless steel, platinum, gold, titanium,tantalum, niobium, polymeric materials and combinations thereof.Desirably, the elongate wires may include nitinol. The elongate wiresmay be composite wires for improved radiopacity. The elongate wires mayhave an inner core radiopaque material selected from the groupconsisting of gold, barium sulfate, ferritic particles, platinum,platinum-tungsten, palladium, platinum-iridium, rhodium, tantalum orcombinations thereof and an outer portion of nitinol.

In another aspect of the present invention, a stent delivery anddeployment system includes (i) a delivery catheter having a distal end;(ii) an elongate radially self-expanding stent having a distal endadjacent the distal end of the catheter; (iii) an elongate sheathretractably positioned about the stent so as to maintain the stent in aradially compressed delivery condition about the distal end of thecatheter; and (iv) a retaining band positioned adjacent the distal endof the stent, the retaining band being retractable with the sheath so asto allow longitudinally progressive and radial expansion of the stentupon the retraction of the sheath for deploying the stent. The retainingband may be positioned at the distal end of the stent, may be positionedbetween the stent and the sheath, may be positioned external to thesheath and combinations thereof. The retaining band may include aradiopaque marker. The band may be imbedded into the sheath. The bandmay be formed of a radiopaque material.

In another aspect of the present invention, a method of delivering anddeploying an expandable stent includes the steps of (i) disposing aradially expanding stent at a distal end of a delivery catheter; (ii)positioning a retractable sheath having a retaining band adjacent adistal end of the stent over the stent so as to maintain the stent in aradially compressed delivery condition; and (iii) retracting the sheathand the retaining band with respect to the distal end of the catheter toallow longitudinal progressive expansion of the stent. The sheath andthe band may be retracted together. The band may be imbedded into thesheath. The retaining band may include a radiopaque marker. Thepositioning step may include positioning the band at the distal end ofthe stent.

In another aspect of the present invention, a system for locating astent for delivery and deployment at an intraluminal site includes (i) adelivery catheter having a distal end; (ii) an elongate deployable stentmounted to the distal end of the catheter; and (iii) a radiopaque markeron the distal end of the catheter; the stent being mounted on the distalend to overlie the marker. The stent may be a distensible stent. Themarker may be positioned adjacent one end of the stent. The stent mayhave a distal end and a proximal end and the marker may positionedadjacent the proximal end.

A method of deploying a stent at a damaged vessel site includes the stepof (i) providing a catheter having a delivery end and a radiopaquemarker adjacent there to; (ii) positioning an expandable stent on thedelivery end so as to overlie the marker; (iii) placing the marker at alocation proximal to the damaged vessel site; and (iv) allowing thestent to expand across the damaged vessel site. The marker may be placedbefore the damaged vessel site to ensure positioning of the expandedstent across the damaged vessel site.

A stent delivery and deployment system may include (i) a deliverycatheter having a distal end; (ii) an elongate radially self-expandingstent having a distal end adjacent the distal end of the catheter, thestent including a plurality of wires arranged to form a hollow tubularstructure having a tubular wall to define an interior surface and anexterior surface and having opposed open first and second ends, whereinthe wires terminate at the second open end and adjacently juxtaposedwires are welded at the second open end with a welding material toprovide welds, and further wherein ends of the terminated wires aresmoothed to remove sharp edges from the wire ends and to provide alongitudinally extending wire portion at the wire ends; (iii) anelongate sheath retractably positioned about the stent so as to maintainthe stent in a radially compressed delivery condition about the distalend of the catheter; and (iv) a retaining band positioned adjacent thedistal end of the stent, the retaining band being retractable with thesheath so as to allow longitudinally progressive and radial expansion ofthe stent upon the retraction of the sheath for deploying the stent.

A stent delivery and deployment system may also include (i) a deliverycatheter having a distal end; (ii) an elongate radially self-expandingstent having a distal end adjacent the distal end of the catheter, thestent including a plurality of wires arranged to form a hollow tubularstructure having a tubular wall to define an interior surface and anexterior surface and having opposed open first and second ends, whereinthe wires terminate at the second open end and adjacently juxtaposedwires are welded at the second open end with a welding material toprovide first welds, wherein at least one of the adjacently juxtaposedstent wires are extended past the welds and looped such that theextended end abuts a proximal pair of stent wires; and further whereinthe extended and looped wire is welded with a welding material to theproximal pair of wires with second welds which are longitudinally offsetfrom the first welds; (iii) an elongate sheath retractably positionedabout the stent so as to maintain the stent in a radially compresseddelivery condition about the distal end of the catheter; and (iv) aretaining band positioned adjacent the distal end of the stent, theretaining band being retractable with the sheath so as to allowlongitudinally progressive and radial expansion of the stent upon theretraction of the sheath for deploying the stent.

A stent delivery and deployment system may include (i) a deliverycatheter having a distal end; (ii) an elongate radially self-expandingstent having a distal end adjacent the distal end of the catheter, thestent including a plurality of wires arranged to form a hollow tubularstructure having a tubular wall to define an interior surface and anexterior surface and having opposed open first and second ends, whereinthe wires at the first end are arranged in a series of closed loops witheach loop having an apex defined by a bend in one of the wires andhaving an opposed base defined by crossing of adjacent wires, whereinthe apex of adjacent closed loops are longitudinally offset from one andthe other; (iii) an elongate sheath retractably positioned about thestent so as to maintain the stent in a radially compressed deliverycondition about the distal end of the catheter; and (iv) a retainingband positioned adjacent the distal end of the stent, the retaining bandbeing retractable with the sheath so as to allow longitudinallyprogressive and radial expansion of the stent upon the retraction of thesheath for deploying the stent.

The invention being thus described, it will now be evident to thoseskilled in the art that the same may be varied in many ways. Suchvariations are not to be regarded as a departure from the spirit andscope of the invention and all such modifications are intended to beincluded within the scope of the following claims.

1. An implantable stent comprising: a plurality of elongate wires braided to form a hollow tubular structure having a tubular wall to define an interior surface and an exterior surface and having opposed open first and second ends; wherein said opposed open first and second ends are atraumatic ends, wherein said wires terminate at said second end; wherein said wires at said first end are arranged in a series of closed loops with each loop having an apex defined by a bend in one of said wires and having an opposed base defined by crossing of adjacent wires; and further wherein said apex of adjacent closed loops are longitudinally offset from one and the other.
 2. The stent of claim 1, wherein said wires comprise composite wires to enhance visibility of the wires to provide improved external imaging of the wires in the body.
 3. The stent of claim 2, wherein the enhanced visibility is enhanced radiopacity and the external imaging is fluoroscopic or x-ray visualization.
 4. The stent of claim 2, wherein said elongate composite wires are metallic wires having an outer metallic portion comprising a first metal and an inner metallic core portion comprising a second metal, wherein said first metal is different from said second metal.
 5. The stent of claim 4, wherein said second metal of said inner core comprises a radiopaque material selected from the group consisting of gold, barium sulfate, ferritic particles, platinum, platinum-tungsten, palladium, platinum-iridium, rhodium, tantalum or combinations thereof.
 6. The stent of claim 4, wherein said first metal of said outer portion comprises nitinol.
 7. The stent of claim 1, wherein said atraumatic ends are free of any loose wire ends.
 8. The stent of claim 1, wherein adjacently juxtaposed wires are securably joined at said second open end to provide first securably joined regions, wherein at least one of said adjacently juxtaposed stent wires are extended past said first securably joined regions and further wherein said extended and looped wire is securably joined to said proximal pair of wires with second securably joined regions to define closed loop wire ends.
 9. The stent of claim 8, wherein said wires are securably joined by welding said wires and further wherein said securably joined regions are welds.
 10. The stent of claim 1, wherein adjacently juxtaposed wires at said second open end are securably joined to provide securably joined regions, wherein ends of said terminated wires are smoothed to remove sharp edges from said wire ends.
 11. The stent of claim 10, wherein said wires are securably joined by welding said wires and further wherein said securably joined regions are welds.
 12. An implantable stent comprising: a plurality of elongate wires braided to form a hollow tubular structure having a tubular wall to define an interior surface and an exterior surface and having opposed open first and second ends; wherein said opposed open first and second ends are atraumatic ends; wherein said wires terminate at said second open end, and adjacently juxtaposed wires are securably joined at said second open end to provide first securably joined regions; wherein at least one of said adjacently juxtaposed stent wires are extended past said first securably joined regions and looped such that the extended end abuts a proximal pair of stent wires; and further wherein said extended and looped wire is securably joined to said proximal pair of wires with second securably joined regions which are longitudinally offset from said first securably joined regions.
 13. The stent of claim 12, wherein said wires are securably joined by welding said wires and further wherein said securably joined regions are welds.
 14. The stent of claim 13, wherein said first and said second welds have a substantially same longitudinally extending extend.
 15. The stent of claim 13, wherein said first and said second welds have a longitudinally extending portions which overlap one and the other.
 16. The stent of claim 1, wherein said stent is partially or fully coated with a polymeric material.
 17. The stent of claim 1, further comprising a hollow tubular graft disposed partially or fully over said interior or said exterior surface.
 18. The stent of claim 17, wherein said graft is a polymeric material.
 19. The stent of claim 18, wherein said polymeric material is selected from the group consisting of polyester, polypropylene, polyethylene, polyurethane, polynaphthalene, polytetrafluoroethylene, expanded polytetrafluoroethylene, silicone, and combinations thereof.
 20. The stent of claim 12, wherein said wires comprise composite wires to enhance visibility of the wires to provide improved external imaging of the wires in the body. 